Rev_Circuits KEY

KEY
Name: ________________________
614
Block: ____
Date: ____/____/____
Review: Electric Current and Circuits (614) (KEY)
1. Describe the primary energy transformation takes place with a battery when it is in a
circuit. (name at least 2 forms of energy in your explanation)
A battery converts CHEMICAL energy into
ELECTRICAL energy.
2. A light bulb changes electrical energy into what type(s) of energy?
A light bulb changes electrical energy into LIGHT
(and HEAT ) energy.
3. Do batteries provide direct current or alternating current?
DIRECT CURRENT
4. Do wall outlets provide direct current or alternating current?
ALTERNATING CURRENT
5. Draw the schematic symbol used for a battery:
6. Draw the schematic symbol used for a light bulb:
7. Draw the schematic symbol used for a resistor:
Standard(s): 5.1, 5.2, 5.3
TA: _____________
Independence Level: __________%
Assistance, coaching, prompting: __________________________________________________
8. Switches:
a. Draw the schematic symbol used for a switch.
b. What are switches used for and how do they work?
Switches are used to turn things on and off. When they
are in the off position, the circuit is OPEN and current
cannot flow.
9. What does the following symbol represent? What is it used for?
A
This is a picture of an AMMETER. It is
used to measure CURRENT.
10. Series Circuits:
a. Draw a circuit diagram (using the symbols learned in class) that shows 2 light
bulbs in series.
b. If one of the bulbs breaks, what happens to the other bulb? Why does this
happen?
If one bulb breaks, the other bulb DOES NOT light. This
is because there is a BROKEN path.
11. Parallel Circuits:
a. Draw a circuit diagram (using the symbols learned in class) that shows 2 light
bulbs in parallel.
b. If one of the bulbs breaks, what happens to the other bulb? Why does this
happen?
If one bulb breaks, the other bulb DOES light. This is
because there is still an UNBROKEN path.
12. Look at the following diagram. How many amperes of current will flow through the
ammeter? SHOW YOUR WORK IN THE SPACE BELOW.
6V
Knowns:
2Ω
Formula & Calculations:
V=6V
A
A
I=?
R=2Ω
I = 3 Amperes
13. Look at the following diagram. How many amperes of current will flow through the
ammeter? SHOW YOUR WORK IN THE SPACE BELOW.
4.5 Ω
Formula & Calculations:
V = 12 V
I=?
A
A
12 V
Knowns:
R = 4.5 Ω
I = 2.7 Amperes
14. Look at the following diagram. What is the value of the resistor? SHOW YOUR
WORK IN THE SPACE BELOW.
Formula & Calculations:
Knowns:
V=9V
9V
R=?
I = 2.5 A
A
A
2.5 A
R=?
R = 3.6 Ohms
15. Look at the following diagram. What is the value of the resistor? SHOW YOUR
WORK IN THE SPACE BELOW.
Formula & Calculations:
100 V
Knowns:
R=?
V = 100 V
I=4A
A
A
4A
R=?
R = 25 Ohms
16. What voltage battery should be used so that 0.4 Amperes of current flow through an
item with a resistance of 50 ohms? SHOW YOUR WORK!
Knowns:
Formula & Calculations:
V= ?
I = 0.4 A
R = 50 ohms
V = 20 Volts
17. Suppose a light bulb with a resistance of 3 ohms is attached to a 9 volt battery. How
much current flows through the light bulb? SHOW YOUR WORK!
Knowns:
Formula & Calculations:
V=9V
I=?
R = 3 ohms
I = 3 Amperes
18. 10 Amps of current flow through an appliance. If the voltage is 120 Volts, what is the
power rating of the appliance? SHOW YOUR WORK!
Knowns:
Formula & Calculations:
V = 120 V
I = 10 A
P = 1200 Watts
P=?
Key Term Review: Match each term in Column B with its definition in Column A. Write
the correct letter in the space provided. Each term is used once and only once.
Column A
D
_______
1. atomic particle with a negative electric charge
I
_______
2. material through which electric charges do not flow
easily
J
_______
3. flow of electric charges through a conductor
Column B
a. proton
b. alternating current
c. parallel circuit
d. electron
L
_______
4. switch that opens a circuit if too much current is flowing
e. electric circuit
_______
5. circuit in which electric current follows only one path
F
f. series circuit
N
_______
6. material through which electric charges flow easily
A
_______
7. atomic particle with a positive electric charge
_______
8. current in which electrons change direction at a regular
B
rate
C
_______
9. circuit in which electric current can follow more than
one path
R
_______
10. the rate at which work is done.
O
_______
11. unit used to measure resistance
K
_______
12. energy available to move electric charges through a
wire
E
_______
13. path that an electric current follows
P
_______
14. the units used for power
G
_______
15. opposition to the flow of electric current
M
_______
16. unit used to measure electric current
Q
_______
17. the units used for energy
H
_______
18. unit used to measure voltage
g. resistance
h. volt
i. insulator
j. electric current
k. voltage
l. circuit breaker
m. ampere
n. conductor
o. ohm
p. Watt
q. Joule
r. power
OLD MCAS QUESTIONS:
A
______1. An electric circuit is shown below. The accompanying table shows the current
measured at different levels of resistance.
Resistance
(Ω)
0.10
0.50
2.5
10.0
Current
(A)
15.0
3.0
0.60
0.15
Based on the data shown in the table, what is the voltage drop across the
variable resistor?
A. 1.5 V
B. 6 V
C. 9 V
D. 12 V
A
______2.
Mr. Jenkins constructed a circuit consisting of a variable source, wires, and a
resistor. In order to triple the amount of current, how should he change the
voltage of the source?
A. make the voltage three times larger
B. make the voltage one-third as great
C. make the voltage nine times larger
D. make the voltage one-ninth as great
D
______3. What is the voltage in a circuit with a current of 3 Amps and a total resistance
of 12 Ω?
A. 0.25 V
B. 4 V
C. 15 V
D. 36 V
B
______4. The circuit diagram below shows three resistors, an ammeter, and a battery.
How much current flows through the ammeter?
A. 1.0 A
B. 6.0 A
C. 13.0 A
D. 24.0
C
______5.
Students in a physics lab are studying the circuit shown in the diagram below.
Which of the following options will double the current through the ammeter?
A. replacing the battery with a 5 V battery
B. adding a 30 Ω resistor in parallel with R
C. replacing the resistor with a 30 Ω resistor
D. adding a second 60 Ω resistor in series with R
B
______6. A 72 W navigation unit on a commercial aircraft has a 24 V power supply and
uses 3 A of electric current. What is the electrical resistance of the navigation
unit?
A. 4 Ω
B. 8 Ω
C. 13 Ω
D. 22 Ω
D
______7.
The diagram below shows an incomplete circuit due to a break in the wire at
point X.
A student is testing materials to see if they
conduct electricity. The student places each
item shown at position X, making sure the
object is in contact with the loose end of each
wire. Which item will electricity flow through,
causing the bulb to light?
C
______8. When a light bulb is turned on, energy changes from one form to another.
Which of the following best describes this change?
A. sound energy to light energy
B. nuclear energy to light energy
C. electrical energy to light energy
D. magnetic energy to light energy
A
______9. Marta has a radio in her room. It requires electricity in order to play. Which of
the following is necessary in order for electricity to move from the source to
the radio?
A. a circuit
B. a magnet
C. a light bulb
D. an insulator
D
______10.
The figures below show a light bulb connected to a battery in two different
ways.
When the switch in Figure 1 is closed the bulb will light. A plastic ring is
inserted in the circuit as shown in Figure 2. What will happen when the switch
is closed in Figure 2?
A. The bulb will light just as it did in Figure 1.
B. The bulb will be brighter than it was in Figure 1.
C. The bulb will light, but will be less bright than it was in Figure 1.
D. The bulb will not light at all.
MCAS Open Response Questions: Please answer each of the
following questions in the boxes below the questions. Label all parts.
1. Look at the objects shown below.
Some of these objects are conductors of electricity and some are insulators.
a. List all the objects that are conductors.
b. List all the objects that are insulators.
c. Describe the difference between a conductor of electricity and an insulator of
electricity.
A. The following items are conductors:
-PAPER CLIP
-COPPER TUBING
-CLOTHES HANGER (ASSUMING IT IS METAL)
B. The following items are insulators:
-RUBBER BAND
-GLASS TUBE
C. The difference between a conductor of electricity and an
insulator of electricity is that the CONDUCTOR allows
charges to flow through it easily while the INSULATOR
does not. This is because the electrons in the conductor are
LOOSELY bound.
Written Response Answer the following questions in complete sentences in the box
below the question.
2. Kamaria is hanging a string of decorative lights. When she plugs the lights in, she
notices that one light in the string is burned out. The rest of the lights are still lit. Are
the lights wired in a series circuit or in a parallel circuit? How do you know?
The lights are wired in a PARALLEL circuit. I know this because
in a SERIES circuit all of the lights go out when one light goes
out. This is because in a SERIES circuit the current has ONLY
ONE path to follow, and if a bulb is broken, there is a break in
the circuit and CURRENT STOPS EVERYWHERE. In a parallel
circuit, when a bulb is broken, there are still other unbroken
paths, so the lights still light.
3. What are the forms of energy involved in a simple circuit? There are four major
forms of energy involved. Write two to three sentences discussing the energy
transformations that take place.
CHEMICAL potential energy is stored in the battery. The battery
converts the CHEMICAL potential energy to ELECTRICAL
energy. The electrons flowing through the wires have KINETIC
energy. When the electrons flow through the light bulb, the bulb
converts the ELECTRICAL energy into HEAT and LIGHT energy.